This is one of the most awful movies I've had the misfortune of picking up. Don't get me wrong, I love a good zombie flick, but this wasn't one of them.
...Might as well (from the opening scenes, at least) been called 'Titty Zombies from Outer Space'. It had absolutely nothing to do with the other movie or the video game (as far as I could tell.)
The best aspect of the film is how the two main characters can get covered with so much blood and remain so nonplussed. I would certainly suggest giving this one and miss and staying with a safer zombie pleaser like '28 Days Later' or 'Dawn of the Living Dead' (the remake, of course, unless you're into some serious campy action.)